Axonal dysfunction prior to neuropathy onset in type 1 diabetes

Background The present study was undertaken to determine whether there were changes evident in axonal membrane function prior to the onset of neuropathy in patients with type 1 and type 2 diabetes. Methods From a cohort of 110 consecutive referrals, nerve excitability was investigated in 40 diabetic patients without clinical evidence of neuropathy (20 type 1 diabetic patients and 20 type 2 diabetic patients). Groups were matched for gender, disease duration and HbA1c. Studies were also undertaken in two control groups, younger controls and older controls, matched for age and gender with the diabetic cohorts. Results Subjects with type 1 diabetes demonstrated significant nerve excitability abnormalities when compared with younger normal controls. Specifically, type 1 subjects showed a significant reduction at multiple time points in both depolarising and hyperpolarising threshold electrotonus. Additionally, the relative refractory period was prolonged (type 1, 3.19 ms; younger normal controls, 3.0 ms; p